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software/liblitedram/sdram: Add sdram_tck_taps variable and use it internally to avoid un-needed accesses to CSRs.

This commit is contained in:
Florent Kermarrec 2021-04-28 11:22:07 +02:00
parent 87c0e30cef
commit c50989be8e
1 changed files with 7 additions and 5 deletions
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12
litex/soc/software/liblitedram/sdram.c
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@ -254,6 +254,7 @@ void sdram_mode_register_write(char reg, int value) {
/* Write Leveling */ /* Write Leveling */
/*-----------------------------------------------------------------------*/ /*-----------------------------------------------------------------------*/
int _sdram_tck_taps;
int _sdram_write_leveling_bitslips[16]; int _sdram_write_leveling_bitslips[16];
#ifdef SDRAM_PHY_WRITE_LEVELING_CAPABLE #ifdef SDRAM_PHY_WRITE_LEVELING_CAPABLE
@ -392,7 +393,7 @@ static int sdram_write_leveling_scan(int *delays, int loops, int show)
int ok; int ok;
err_ddrphy_wdly = SDRAM_PHY_DELAYS - ddrphy_half_sys8x_taps_read(); err_ddrphy_wdly = SDRAM_PHY_DELAYS - _sdram_tck_taps/4;
sdram_write_leveling_on(); sdram_write_leveling_on();
cdelay(100); cdelay(100);
@ -537,7 +538,7 @@ static void sdram_write_leveling_find_cmd_delay(unsigned int *best_error, unsign
int delay_count = 0; int delay_count = 0;
for (int i=0; i < SDRAM_PHY_MODULES; ++i) { for (int i=0; i < SDRAM_PHY_MODULES; ++i) {
if (delays[i] != -1) { if (delays[i] != -1) {
delay_mean += delays[i] + ddrphy_half_sys8x_taps_read(); delay_mean += delays[i] + _sdram_tck_taps/4;
delay_count += 1; delay_count += 1;
} }
} }
@ -545,7 +546,7 @@ static void sdram_write_leveling_find_cmd_delay(unsigned int *best_error, unsign
delay_mean /= delay_count; delay_mean /= delay_count;
/* We want the higher number of valid modules and delay to be centered */ /* We want the higher number of valid modules and delay to be centered */
int ideal_delay = (SDRAM_PHY_DELAYS - ddrphy_half_sys8x_taps_read())/2; int ideal_delay = (SDRAM_PHY_DELAYS - _sdram_tck_taps/4)/2;
int error = ideal_delay - delay_mean; int error = ideal_delay - delay_mean;
if (error < 0) if (error < 0)
error *= -1; error *= -1;
@ -575,7 +576,8 @@ int sdram_write_leveling(void)
int cdly_range_end; int cdly_range_end;
int cdly_range_step; int cdly_range_step;
printf(" tCK/4 taps: %d\n", ddrphy_half_sys8x_taps_read()); _sdram_tck_taps = ddrphy_half_sys8x_taps_read()*4;
printf(" tCK equivalent taps: %d\n", _sdram_tck_taps);
if (_sdram_write_leveling_cmd_scan) { if (_sdram_write_leveling_cmd_scan) {
/* Center write leveling by varying cdly. Searching through all possible /* Center write leveling by varying cdly. Searching through all possible
@ -588,7 +590,7 @@ int sdram_write_leveling(void)
if (_sdram_write_leveling_cdly_range_end != -1) if (_sdram_write_leveling_cdly_range_end != -1)
cdly_range_end = _sdram_write_leveling_cdly_range_end; cdly_range_end = _sdram_write_leveling_cdly_range_end;
else else
cdly_range_end = 2*ddrphy_half_sys8x_taps_read(); /* Limit Clk/Cmd scan to 1/2 tCK */ cdly_range_end = _sdram_tck_taps/2; /* Limit Clk/Cmd scan to 1/2 tCK */
printf(" Cmd/Clk scan (%d-%d)\n", cdly_range_start, cdly_range_end); printf(" Cmd/Clk scan (%d-%d)\n", cdly_range_start, cdly_range_end);
if (SDRAM_PHY_DELAYS > 32) if (SDRAM_PHY_DELAYS > 32)